In certain cases, for example on board ships, on civil engineering worksites, such as bridges, dams, and the like, or on the running tracks of traveling cranes, personnel may be required to move over a path situated at a great height which, on at least one side, cannot be provided with a railing. Personnel must then wear a safety harness consisting of a belt adapted to be hooked to a cable or other elongated element fixed along the path of movement.
The device described in French Patent No. 1,356,533, for example, consists of a cable fixed at both ends and stretched parallel to the movement path. An element hooking to the safety harness can slide along this cable. If the cable is not very long, the hooking element can slide from one end to the other. However, it is generally necessary for the cable to be carried by regularly spaced support elements. A system must then be be provided which enables the sliding hooking element to pass over each support without having to be unhooked. For this purpose the patent discloses a particular support element provided with a spiral slot enabling the support element to pass without being unhooked, while still supporting the cable. However, a system of this kind requires relatively complicated machining and makes it necessary for the person secured to pay particular attention to the passage of the hooking element over the supports.